Thermoplastic resins, such as vinylchloride resins, polyethylene, polypropylene, polyester, polystyrene, polycarbonate, a methacrylate resin, and ABS resin, are excellent in physical properties, and have economic advantage and applicability, and have been widely used in various fields. However, since these resins have high melt viscosity and low fluidity, and are susceptible to thermal decomposition, there are problems in processability that they have a narrow processable condition in molding, and that they tend to stick or adhere to a metal surface of a device in processing at a high temperature.
Now there have been proposed many techniques in order to solve the above-mentioned problems in processability.
Applicability of vinylchloride resins, polyethylene, polypropylene, polyester, polystyrene, polycarbonate, a methacrylate resin, ABS resin and the like can be improved by physically blending modifiers such as a lubricant, a stabilizer, a colorant, a filler, a pigment, a cross-linking agent, a tackifier, a plasticizer, a processing aid, an impact modifier and a modifier for thermal deformation temperature, before processing.
Moreover, in order to improve molding processability at molding of vinylchloride resins, polyethylene, polypropylene, polyester, polystyrene, polycarbonate, a methacrylate resin, and ABS resin, some of copolymers compatible with those resins have been investigated as a processing aid.
For example, there have been proposed a method in which a copolymer of methyl methacrylate and styrene is added to vinylchloride resins (Japanese Examined Patent Publication No. 32-4140 (1957)), a method in which a copolymer of styrene and acrylonitrile is added thereto (Japanese Examined Patent Publication No. 29-5246 (1954)), a method in which a copolymer mainly containing methyl methacrylate is added thereto (Japanese Examined Patent Publication No. 40-5311 (1965)), a method in which a copolymer of styrene and alkyl acrylate is added thereto (Japanese Examined Patent Publication No. 37-1384 (1962)) and the like. Secondary processability such as an increase in melting rate of vinyl chloride resins and an increase in tensile elongation at a high temperature can be improved, but there is no effect in reducing adhesiveness to a metal face of the molding device.
Thereafter, in order to reduce adhesiveness to a metal surface of a molding device, there has been investigated a method in which a copolymer of styrene, an alkyl (meth)acrylate and (meth)acrylate having an oxygen atom in addition to an ester bond is added to vinyl chloride resins (Japanese Examined Patent Publication No. 58-56536 (1983)). In this method the adhesiveness is proved to be improved, but this method cannot always satisfy the demands in the market.